The present invention relates to a fixing roller base body holding device utilized for manufacturing fixing rollers, which can be employed for image forming apparatus, such as copiers, printers, facsimile devices, etc., and a method for manufacturing fixing rollers and image forming apparatus.
The present applicant has proposed the image forming apparatus, comprising a fixing roller, which can be instantaneously heated up, or rapidly heated up in a short time, as set forth in Tokuganhei 10-28917.
In Tokuganhei 10-28917, there is disclosed a fixing roller, in which Pyrex glass, a ceramic material made of sapphire (Al2o3), CaF2, etc. or a transparent resin material made of polyimide, polyamide, etc., is employed for the roller base body of the fixing roller, and a heat-rays absorbing layer, mingled with powders of carbon black, graphite, iron black (Fe3O2), or various kinds of ferrite materials, etc., is formed on the outer circumferential surface of the roller base body by baking or applying process, so that the heat-rays absorbing layer effectively absorbs such heat-rays irradiated from a halogen lump or a xenon lump disposed interior of the roller base body, and further, a fluorine resin (PFA) tube, covering the outer circumferential surface of the heat-rays absorbing layer, or a release layer, formed by applying a fluorine resin paint on it, is provided.
Further, as other structures of the fixing roller, there are also disclosed embodiments, in which a heat-rays transmittable rubber layer made of silicon rubber, mingled with powders of metal oxide materials, such as silica, alumina, magnesium oxide, etc., is formed on the outer circumferential surface of the roller base body, and further, an integral heat-rays absorbing layer, integrated with a heat-rays absorbing layer and a release layer, is formed by compounding a heat-rays absorbing material mingled with powders of carbon black, graphite, iron black, or various kinds of ferrite materials and its compounds, capper oxide, cobalt oxide, red oxide, etc., and a fluorine resin paint, working as both binder and release member.
The fixing roller, disclosed in the above, is very useful, since the surface temperature of it can reach to an allowable temperature for its fixing operation within a very short time.
Conventionally, however, there has been no concrete proposal for a configuration to form a kind of layer, such as a heat-rays absorbing layer, etc., on the outer circumferential surface of the roller base body.
As an example, a method of forming a layer, in which a pipe, serving as a roller base body, is disposed at a predetermined position in an interior of a casting mold, and, for instance, a melted rubber is poured into the casting mold to be cured between the pipe and the casting mold, may be applicable.
The present applicant performed an experiment in such a configuration that the roller base body is integrated with a mold by supporting the roller base body interior of the mold by means of flanges, and a part of the flange is inserted into each of both end openings of the roller base body to position the roller base body at a predetermined position in the mold.
As a result of the experiment, the present applicant has found a problem that, especially when a cylindrical glass hereinafter, also referred to as a glass pipe) is employed for the roller base body, damages of the both end portions of the glass pipe occur.
Concretely speaking, although it is desirable that the flanges are made of a metal material, such as iron, etc., from the handling point of view, when the flanges are heated up by the high temperature melted rubber injected into the mold, the flanges push the glass pipe expanding, due to the difference of thermal expansion between glass and metal, resulting in the abovementioned damages.
To overcome the abovementioned problem, it may be possible to introduce an allowance between them. Such the allowance, however, make it impossible to precisely adjust the center axes of both the glass pipe and the mold at the same position, resulting in an uneven thickness of the layer formed on the glass pipe.
Further, when the fixing roller, which employs the glass pipe for the roller base body, is mounted onto a frame of the fixing device with a normal bearing, it has been difficult to obtain a sufficient accuracy.
In other words, since the glass pipe is low in the accuracy and has variations in the dimension, an appropriate bearing, having a larger inner diameter, may be employed for supporting the glass pipe. In such structure, however, the excessive allowance between the glass pipe and the bearing makes it difficult to adjust the pressing roller, which rotates while pressing the fixing roller, in parallel with the fixing roller, and as a result, causes fixing defects.
To overcome the abovementioned drawbacks in conventional roller body holding devices, it is a main object of the present invention to provide a roller body holding device, which makes it possible to effectively hold a roller body in a simple structure. Incidentally, a term of xe2x80x9crubberxe2x80x9d, described in the present specification, indicates a xe2x80x9csynthetic elastomerxe2x80x9d.
Accordingly, to overcome the cited shortcomings, the abovementioned object of the present invention can be attained by methods for manufacturing a fixing roller and roller body holding devices described as follow.
(1) A method for manufacturing a fixing roller, comprising steps of: press-fitting flanges into a roller body, shaped in a hollow cylinder, from each of both end openings of the roller body with putting an elastic material between each of the flanges and the roller body; installing a roller body holding device, which includes the flanges press-fitted into the roller body, at a predetermined position in a shaping mold; injecting a melted rubber into a space between the roller body and the shaping mold from an injection opening; and curing the melted rubber injected into the space.
(2) The method of item 1, wherein the roller body is made of glass, and the melted rubber contains a heat absorbing material.
(3) The method of item 1, wherein a heat-resistant tube is provided on an inner circumferential surface of the shaping mold, and integrated with the roller body by curing the melted rubber.
(4) The method of item 1, wherein the elastic material is provided on outer circumferential surfaces of the flanges, so as to shape a ring.
(5) The method of item 1, wherein the flanges are fitted into a shaft, which is inserted into an interior of the roller body.
(6) The method of item 1, wherein the elastic material is shaped in a ring, and equipped in a groove, which is formed in a circumferential direction on outer surfaces of the flanges.
(7) The method of item 1, wherein a plurality of the elastic materials are equipped on circumferential surfaces of the flanges, spacing each other with appropriate distances.
(8) The method of item 1, wherein the elastic material is detachable with respect to the flanges.
(9) The method of item 1, wherein the elastic material is made of either a silicon rubber or a fluorine rubber.
(10) The method of item 1, wherein the roller body, shaped in the hollow cylinder, is made of glass.
(11) A method for manufacturing a fixing roller, comprising steps of: installing a roller body, shaped in a hollow cylinder, at a predetermined position in a shaping mold by pushing both ends of the roller body by means of holding members, which are movable in an center axis direction of the roller body; injecting a melted rubber into a space between the roller body and the shaping mold from an injection opening; and curing the melted rubber injected into the space.
(12) The method of item 11, wherein each of the holding members comprises a cone-shaped surface, which contacts each of both end edges of the inner circumferential surface of the roller body.
(13) The method of item 12, wherein each of the holding members is urged in the center axis direction of the roller body by an urging member, so that the cone-shaped surface pushes each of both end edges of the inner circumferential surface of the roller body to hold the roller body.
(14) An image forming apparatus, comprising: a roller-type fixing device, in which a bearing is fitted on an outer circumferential surface of a fixing roller, manufactured by the method cited in item 1 or item 11, to support the fixing roller.
(15) A roller body holding device for holding a roller body, shaped in a hollow cylinder, comprising: a flange, each of which is press-fitted into the roller body from each of end openings of the roller body; and an elastic material disposed between the flange and the roller body.
(16) The roller body holding device of item 15, wherein the elastic material is provided on an outer circumferential surface of the flange, so as to shape a ring.
(17) The roller body holding device of item 15, wherein the flange is fitted into a shaft, which is inserted into an interior of the roller body.
(18) The roller body holding device of item 15, wherein the elastic material is shaped in a ring, and equipped in a groove, which is formed in a circumferential direction on an outer surface of the flange.
(19) The roller body holding device of item 15, wherein a plurality of the elastic materials are equipped on a circumferential surface of the flange, spacing each other with appropriate distances.
(20) The roller body holding device of item 15, wherein the elastic material is detachable with respect to the flange.
(21) The roller body holding device of item 15, wherein the elastic material is made of either a silicon rubber or a fluorine rubber.
(22) The roller body holding device of item 15, wherein the roller body, shaped in a hollow cylinder, is made of glass.
(23) A roller body holding device for holding a roller body, shaped in a hollow cylinder, comprising: a holding member, which is movable in an center axis direction of the roller body and disposed at each of both ends of the roller body, to push both ends of the roller body to hold the roller body; a fixed mold, disposed at one end of the roller body, to movably accommodate the holding member; and a movable mold, disposed at another end of the roller body, to movably accommodate the-holding member.
(24) The roller body holding device of item 23, wherein the holding member comprises a cone-shaped surface, which contacts each of both end edges of the inner circumferential surface of the roller body.
(25) The roller body holding device of item 23, wherein the holding member is urged in the center axis direction of the roller body by an urging member, so that the cone-shaped surface pushes each of both end edges of the inner circumferential surface of the roller body to hold the roller body.
(26) A roller body holding device for holding a roller body, shaped in a hollow cylinder, comprising: a flange, which is press-fitted onto an outer surface of the roller body at each of end portions of the roller body; and an elastic material disposed between the flange and the roller body.
(27) The roller body holding device of item 26, wherein the elastic material is provided on an inner circumferential surface of the flange, so as to shape a ring.
(28) The roller body holding device of item 26, wherein the flange is fitted into a shaft, which is inserted into an interior of the roller body.
(29) The roller body holding device of item 26, wherein the elastic material is shaped in a ring, and equipped in a groove, which is formed in a circumferential direction on an inner surface of the flange.
(30) The roller body holding device of item 26, wherein a plurality of the elastic materials are equipped on a circumferential surface of the flange, spacing each other with appropriate distances.
(31) The roller body holding device of item 26, wherein the elastic material is detachable with respect to the flange.
(32) The roller body holding device of item 26, wherein the elastic material is made of either a silicon rubber or a fluorine rubber.